Protective garments are designed to protect the wearer from hazardous environmental conditions the wearer might encounter. Such garments include those designed to be worn by firefighters and other rescue personnel, industrial and electrical workers, and military personnel.
Standards have been promulgated that govern the performance of such garments (or constituent layers or parts of such garments) to ensure that the garments sufficiently protect the wearer in hazardous situations. For example, National Fire Protection Association (NFPA) 1971 (2013 edition, incorporated herein by this reference) governs the required performance of firefighter garments. NFPA 2112 (2012 edition, incorporated herein by this reference) governs the required performance of industrial worker garments that protect against flash fires. Both of these standards require that the garments and/or individual layers or parts thereof pass a number of different performance tests, including compliance with the thermal protective requirements of having a 4 inch (or less) char length and a 2 second (or less) afterflame when measured pursuant the testing methodology set forth in ASTM D6413 (1999), the entirety of which is hereby incorporated by reference.
To test for char length and afterflame, a fabric specimen is suspended vertically over a flame for twelve seconds. The fabric must self-extinguish within two seconds (i.e., it must have a 2 second or less afterflame). After the fabric self-extinguishes, a specified amount of weight is attached to the fabric and the fabric lifted so that the weight is suspended from the fabric. The fabric will typically tear along the charred portion of the fabric. The length of the tear (i.e., the char length) must be 4 inches or less when the test is performed in both the machine/warp and cross-machine/weft directions of the fabric. A fabric sample is typically tested for compliance both before it has been washed (and thus when the fabric still contains residual—and often flammable—chemicals from finishing processes) and after a certain number of launderings (100 launderings for NFPA 2112 and 5 launderings for NFPA 1971).
NFPA 1971 and NFPA 2112 also contain requirements relating to the extent to which the fabric shrinks when subjected to heat. The thermal shrinkage of the fabric is measured pursuant to the methodology set forth in ISO 17493 (2000, the entirety of which is herein incorporated by reference). To conduct thermal shrinkage testing, marks are made on the fabric a distance from each other in both the machine/warp and cross-machine/weft directions. The distance between sets of marks is noted. The fabric is then suspended in a 500 degree oven for 5 minutes. The distance between sets of marks is then re-measured. The thermal shrinkage of the fabric is then calculated as the percentage that the fabric shrinks in both the machine/warp and cross-machine/weft directions and must be less than the percentage set forth in the applicable standard. For example, NFPA 1971 requires that the fabrics used in the construction of a firefighter's garment exhibit thermal shrinkage of less than <10% in both the machine/warp and cross-machine/weft directions.
Structural fire fighters garments, such as firefighters' turnout gear, typically consist of matching coat and pants and are designed primarily to prevent the wearer from sustaining a serious burn. NFPA compliant turnout gear or garments are typically comprised of three layers: an outer shell, an intermediate moisture barrier, and a thermal barrier lining. The outer shell is usually a woven fabric made from flame resistant fibers and is considered a firefighter's first line of defense. Not only should it resist flame, but it needs to be tough and durable so as not to be torn, abraded, or snagged during normal firefighting activities.
The moisture barrier, while also flame resistant, is present to keep water and harmful chemicals from penetrating and saturating the turnout gear. Excess moisture entering the gear from the outside would laden the firefighter with extra weight and increase his or her load.
The thermal barrier is flame resistant and offers the bulk of the thermal protection afforded by the ensemble. A traditional thermal barrier is a batting made of a nonwoven fabric of flame resistant fibers quilted to a lightweight woven facecloth also made of flame resistant fibers. The batting may be either a single layer of needle-punch nonwoven fabric or multiple layers of spun lace nonwoven fabric. The facecloth is commonly quilted to the batting in a cross-over or chicken wire pattern. The quilted thermal barrier is the innermost layer of the firefighter's garment, with the facecloth typically facing the wearer.
The facecloth fabrics of thermal liners protect the batt from abrasion and are in direct contact with either the firefighters' station wear or skin. Facecloths woven with filament yarns are slicker than facecloths woven with 100% spun yarns. This slickness is desirable for easier donning and doffing of the structural firefighting garment as well as ease of movement when the garment is worn.
There are limited inherently flame resistant filament yarns commercially available which can be used to weave the facecloth fabric and still meet the thermal protective and thermal shrinkage requirements discussed above. The filament yarns used in existing facecloths are made with some version of filament aramid yarn woven with 100% aramid spun yarns, spun yarns with some blend of flame resistant (“FR”) rayon, aramid and nylon, or a combination thereof. These fabrics are expensive, may have a harsh hand “or feel,” do not easily wick sweat away from the skin to relieve heat stress, and are hydrophobic so as to exhibit low moisture regain. The aramid filament yarns used in these fabrics can also be difficult to dye and/or print. There is a need for fabrics (such as, but not limited to, facecloth fabrics) formed with lower cost filament yarns that—whether alone or when attached to another layer (such as a batt)—meet the performance requirements of NFPA 1971 while being inherently wicking, soft, and easily dyeable.